Platelet-Rich Plasma: A HealthCentral Explainer

In 2008, Tiger Woods underwent a controversial procedure to help recover from a torn ACL. The procedure, known then as "blood spinning," involved removing blood from Woods' knee and spinning it in a centrifuge, then reinjecting the substance back into the knee.

The process was designed to separate growth hormones and platelets in the blood from everything else, leaving a potent formula called platelet-rich plasma (PRP), which has since became the accepted terminology for the procedure. At the time, many accused Woods of cheating, especially when the doctor who performed the surgery was arrested for steroid distribution. However, since 2008, a number of high profile athletes – including Kobe Bryant, Alex Rodriguez and Ray Lewis – have undergone procedures involving platelet-rich plasma.

At the time of Woods' procedure, many in the field said that PRP was junk science and that there was no basis to claims that the process could speed recovery times. This did not stop athletes--and many average citizens--from considering the procedure because they were desperate to find a miracle cure for an ailment.

Now, however, a new report from the prestigious Hospital for Special Surgery in New York has backed up what those PRP believers have long contended—the treatment holds great promise.

What's the research?

The study, published in the Clinical Journal of Sports Medicine, found that PRP therapy improved pain and function in cases of osteoarthritis of the knee. The research found that 73 percent of patients who underwent the procedure delayed the progression of osteoarthritis as well.

Osteoarthritis is characterized by the breakdown of the cartilage in the joint – in this case, the cushioning in the knee. When the cartilage breaks down, the person feels pain, stiffness and swelling in the joint that can severely limit mobility. Mild cases of osteoarthritis can be treated with anti-inflammatory drugs or painkilling medication, while more severe cases call for surgery, including arthroscopic surgery (where doctors remove damaged cartilage) and knee replacement surgery (where the entire joint is removed and replaced with a prosthetic).

PRP treatment utilizes the patient's own blood and then concentrates the desirable platelets, according to the research team responsible for the study. The researchers concluded that injecting this PRP solution back into the knee activates growth factors and stem cells, which repair damaged tissue. This could help with recovery from injury – such as Woods' torn ACL – but has also shown promise in stopping the development of osteoarthritis in knees.

Overall, PRP was found useful in reducing pain and stiffness and improving function in patients who underwent the procedure. Pain was found to be reduced by 41.7 percent six months after the process and 55.9 percent over the course of a year. Functional scores improved by 24.3 percent one year after the procedure.

Why is this study different?

This study is the first of its kind to utilize MRIs to track the progress of osteoarthritis in patients given PRP. Those studying the images were unaware of the PRP treatments, and thus, provided an unbiased perspective on the success or failure of the procedures. Additionally, patients were gauged based on their daily abilities and pain and functionality levels, though this type of surveying, where the patient is aware of delivered treatments, could result in some participants benefitting from the placebo effect. For this reason, the evaluation of MRIs was critical in determining the actual impact on the knee cartilage of patients in the study.

The long-term ramifications

PRP treatment appears to advance the trend of biological medicine, in which a person's own body is used to fight back against disease or infection. While PRP is being investigated for the treatment of osteoarthritis, so too are stem cell procedures, based on similar concepts to try to stop the progression of disease.